The present invention relates to fuel cells, and more specifically to water management within a fuel cell.
During fuel cell operation, water droplets frequently form on the surface of gas diffusion layers within the fuel cell. Generally, the water droplets migrate through the gas diffusion layers into gas flow channels. In the gas flow channels, movement of the water can be inhibited by pinning of the three-phase region, commonly referred to as the contact line region. In the contact line region, the gas, liquid and solid phases collide.
A balance between keeping the membrane from becoming too dry or too wet must be maintained for efficient and reliable fuel cell operation. At high current densities, the production of liquid water may exceed the capacity of the gas streams to evaporate the water out of the fuel cell stack and drops of water will appear within the gas flow channels. If the water accumulation becomes too great, then the gas flow channel may become completely blocked by water and the fuel cell will “flood.” Therefore, the water drops must be removed from the gas flow channels for reliable operation. Efficient removal of the product water is an important step in fuel cell operation and enables increased commercial utilization of fuel cells.